<?php
use yii\widgets\ActiveForm;
use yii\helpers\Url;
?>

<?php $form = ActiveForm::begin() ?>

<?= $form->field($model, 'files')->widget('manks\FileInput', [
	'clientOptions' => [
		'pick' => [
			'multiple' => true,
		],
		// 'server' => Url::to('/upload/u2'),
		// 'accept' => [
		// 	'extensions' => 'png',
		// ],
	],
]);
?>

<button>Submit</button>

<?php ActiveForm::end() ?>